Clumping animal litters are typically provided in the form of discrete plural particles. The particles tend to agglomerate into solid masses or clumps when wetted by a liquid, such as animal waste. The art has provided a number of clumping litters. One advantage of clumping litters is that the solid clumps formed upon wetting of the litter can be removed as discrete entities from the remaining litter and can be discarded by the animal owner, leaving behind a quantity of relatively uncontaminated litter. Animal owners, and in particular owners of animals such as house cats, often find the clumping property of such litters to be convenient for periodic cleaning of the animal litter box. Some known animal litters have good ammonia-masking properties. Because ammonia is a breakdown product of the urea found in animal urine, the ability of an animal litter to mask the odor of ammonia is a desired property.
Many clumping animal litters are made from clays and other mineral substrates. Such litters typically include particles of a mineral substrate, which substrate functions as an absorbent and/or odor reducer. The particles may be coated with a liquid-activated adhesive material, such as gelatinized starch, on the surfaces of the particles. When wetted, the adhesive material is activated and causes the discrete litter particles to agglomerate into clumps.
Other litters are made from organic materials. For instance, numerous patents, e.g., U.S. Pat. Nos. 7,757,638; 7,753,002; 6,098,569; 6,216,634; 6,405,677; 6,622,658; and 6,868,802, describe making an animal litter with spent grain germ or spent oil seed meals, grain meal or ground corn.
One known litter product includes corn hominy feed and spent corn germ. Corn hominy feed is a by-product of the dry corn milling process, which produces as main products pearl hominy, hominy grits or table meal corn. Hominy feed is a mixture of corn bran, corn germ, and part of the starchy portion of either yellow or white corn kernels. Normally in a dry milling process, the germ is removed from the corn kernel in a “de-germinator,” and then the corn bran and tip cap are removed. The endosperm is used to produce grits or corn flour. The process produces a number of mill streams (corn fractions) that differ in particle size, composition, and quality. The desired streams are collected and then the by-products and unwanted streams (sometimes called “fine through stock”) are blended with the corn germ and corn bran to form hominy feed. Hominy feed generally contains nine percent protein (minimum), four percent fat (minimum), and six percent fiber (maximum). For example, a typical hominy feed includes 90 percent dry matter, 10.0 percent crude protein, 5 percent fat, 5.6 percent crude fiber, 49.5 percent neutral detergent fiber, 11.7 percent acid detergent fiber, 0.05 percent calcium, and 0.5 percent phosphorus. Corn germ contains about 20 to about 50 percent oil. Other components of corn germ include starch (about 8 percent by weight), protein (about 12 percent by weight), ash (about 2 percent by weight), moisture (about 8 percent by weight) and crude fiber (about 5 percent by weight). In commercial grain milling, grain germ often is extracted (e.g., by solvent or press extraction) to provide a rich source of grain oil, which results in “spent” germ.
Conventional litters often include added oils in an effort to improve agglomeration of the litter particles and to reduce dust during mixing, handling, packaging, and use of the product. For example, U.S. Pat. No. 5,152,250 to Loeb describes mixing granular litter with grain flour to cause agglomeration and mineral oil to cause the flour to adhere to the grains. U.S. Pat. No. 6,053,125 purports to describe oil-coating both heavy density particles and light density particles, such as with mineral oil added at 4 percent by weight of the total weight of the particles.
U.S. Pat. No. 5,230,305 states that the rate of sorption of urine by a natural animal litter is dependent upon the particular natural product and process used to prepare the litter. Thus, if a grain based material was used to prepare the litter, the litter would contain the oils naturally associated with the grain and these oils might decrease the rate of sorption of urine by the litter. In an effort to increase the rate of urine sorption, a wettability enhancing agent is added to the litter and the particle size distribution of the litter is adjusted. The wettability increasing agent could be any material that increases the rate of sorption of an aqueous liquid, such as urine, and may be a surface active agent sprayed onto the surface of the litter particles.
The invention seeks, in some embodiments, to provide an animal litter that differs from the heretofore described litters.